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Hi cgaliher,<br />
<br />
Thanks for the reply. <br />
<br />
Ok I don't mind if the drives appear as external drives or not as long as ai can acess them as a disk for backup purposes.<br />
<br />
guess then I will go with the optopn 1 - Fixed. <br />
<br />
I will also bookmark TechNet.
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Hi cgaliher,

Thanks for the reply.

Ok I don't mind if the drives appear as external drives or not as long as ai can acess them as a disk for backup purposes.

guess then I will go with the optopn 1 - Fixed.

I will also bookmark TechNet.

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<div class="content wysiwyg-content">
I have Hyper-v setup on a Windows 2008R2 Enterprise server.<br />
<br />
I have some virtual servers there too.<br />
<br />
I have a couple of USB drives that I have plugged into the Parent machine. I want these 2 to be seen as external hard disks to all the Virtual machines. &nbsp;I am planing to use these as backup drives.<br />
<br />
I am trying to achieve this by adding the 2 USB disks as Virtual Hard Disks under the Hyper-V manager. <br />
<br />
There are however 3 Disk type options. <br />
1. &quot;Fixed Size&quot;<br />
2. &quot;Dynamically Expanding&quot;<br />
3. &nbsp;&quot;Differencing&quot;<br />
I was hoping the option 3 &nbsp;&quot;Differencing&quot; ( as in the screenshot ) would be the best ?<br />
Is this a &quot;safe&quot; option ? I don't want my Host machine to have issues if I choose the wrong option.<br />
<br />
and if anyone can explain what these optoins are - that would be great too.
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</div>


I have Hyper-v setup on a Windows 2008R2 Enterprise server.

I have some virtual servers there too.

I have a couple of USB drives that I have plugged into the Parent machine. I want these 2 to be seen as external hard disks to all the Virtual machines.  I am planing to use these as backup drives.

I am trying to achieve this by adding the 2 USB disks as Virtual Hard Disks under the Hyper-V manager. 

There are however 3 Disk type options. 
1. "Fixed Size"
2. "Dynamically Expanding"
3.  "Differencing"
I was hoping the option 3  "Differencing" ( as in the screenshot ) would be the best ?
Is this a "safe" option ? I don't want my Host machine to have issues if I choose the wrong option.

and if anyone can explain what these optoins are - that would be great too.

adding a Virtual Hard disk to Hype-V host

Microsoft Virtual Server was a virtualization solution that facilitated the creation of virtual machines on the Windows XP, Windows Vista and Windows Server 2003 operating systems. Virtual machines are created and managed through a web-based interface that relies on Internet Information Services (IIS) or through a Windows client application tool called VMRCplus. Features included Linux guest operating system support, Virtual Disk Precompactor, symmetric multiprocessing (SMP), x64 host operating system support, the ability to mount virtual hard drives on the host machine and additional operating systems support, including Windows Vista, and a volume shadow copy writer.

Microsoft Virtual Server

Windows Server 2008 and Windows Server 2008 R2, based on the Microsoft Vista codebase, is the last 32-bit server operating system released by Microsoft. It has a number of versions, including including Foundation, Standard, Enterprise, Datacenter, Web, HPC Server, Itanium and Storage; new features included server core installation and Hyper-V.

Windows Server 2008

Hyper-V is a native hypervisor; it can create virtual machines on x86-64 systems and supersedes Windows Virtual PC as the hardware virtualization component of the client editions of Windows NT. A server computer running Hyper-V can be configured to expose individual virtual machines to one or more networks. Hyper-V Server supports remote access via Remote Desktop Connection. Administration and configuration of the host OS and the guest virtual machines is generally done over the network.